Stent-graft with bioabsorbable structural support

ABSTRACT

The invention relates to a stent-graft with a bioabsorbable structure and a permanent graft for luminal support and treatment of arterial fistulas, occlusive disease, and aneurysms. The bioabsorbable structure is formed from braided filaments of materials such as PLA, PLLA, PDLA, and PGA and the graft is formed from materials such as PET, ePTFE, PCU or PU.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/498,226, filed Aug. 2, 2006, which is a continuation of U.S. patentapplication Ser. No. 10/674,726, filed Sep. 30, 2003, now U.S. Pat. No.7,108,716, which is a divisional of U.S. application Ser. No.08/993,985, filed Dec. 18, 1997, now U.S. Pat. No. 6,626,939, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to implantable, radiallyexpandable medical prostheses which are frequently referred to asstent-grafts. In particular, the present invention is a self-expandingstent-graft having a bioabsorbable structural component and a permanentgraft component.

Self-expanding stents and methods for fabricating a stent are known andare, for example, shown in the U.S. Pat. Nos. 4,655,771; 4,954,126;5,061,275; and in 5,645,559. Such devices are used within body vesselsof humans for a variety of medical applications. Examples includeintravascular stents for treating stenoses, stents for maintainingopenings in the urinary, biliary, tracheobronchial, esophageal, renaltracts, and vena cava filters. A stent-graft is described in U.S. patentapplication Ser. No. 08/640,253, entitled “Cobalt-Chromium-MolybdenumAlloy Stent and Stent Graft,” filed Apr. 30, 1996 (now U.S. Pat. No.5,891,191).

A delivery device is used to deliver the stent-graft through vessels inthe body to a treatment site. The flexible nature and reduced radius ofthe compressed stent-graft enables it to be delivered through relativelysmall and curved vessels.

All references cited herein, including the foregoing, are incorporatedherein in their entireties for all purposes.

SUMMARY OF THE INVENTION

The present invention relates to a self-expanding stent-graft having abioabsorbable structure such as a stent and a permanent graft bondedtogether with an adhesive. The implantable stent-graft may include atubular, radially compressible, axially flexible and radiallyself-expandable structure made from bioabsorbable elongate filamentsformed in a braid-like configuration and a graft made from materialssuch as polyethylene terephthalate (PET), expandedpolytetrafluoroethylene (ePTFE), polycarbonate urethane (PCU) orpolyurethane (PU). The graft may be adhered to a surface of thebioabsorbable structure or interwoven or braided into the bioabsorbablestructure. The preferred graft of the stent-graft is made of braided,woven, or spray-cast PET, PCU, or PU fibers. The graft may also be madeof film, sheet, or tube such as an ePTFE or PCU material. The graft isdesigned to remain permanently implanted in the body, however, smallamounts of degradation may occur to the graft over time in the bodyenvironment.

The stent-graft generally assumes a substantially tubular form in anunloaded or expanded state when not subjected to external forces and isgenerally characterized by a longitudinal shortening upon radialexpansion and a longitudinal lengthening upon radial contraction.

In a preferred embodiment, the bioabsorbable structure of thestent-graft assembly is a stent which substantially consists of aplurality of elongate polylactide bioabsorbable polymer filaments,helically wound and interwoven in a braided configuration to form atube. The filaments may also be made of poly(alpha-hydroxy acid) such aspoly-L-lactide (PLLA), poly-D-lactide (PDLA), polyglycolide (PGA),polydioxanone, polycaprolactone, polygluconate, polylacticacid-polyethylene oxide copolymers, modified cellulose, collagen,poly(hydroxybutyrate), polyanhydride, polyphosphoester, poly(anunoacids), or related copolymer materials.

Each bioabsorbable material has a characteristic degradation rate in thebody. For example, PGA and polydioxanone are relativelyfast-bioabsorbing materials (weeks to months) and PLA andpolycaprolactone are relatively slow-bioabsorbing materials (months toyears).

PLA, PLLA, PDLA and PGA have a tensile strength of from about 276millions of Pascals (MPa) to about 827 MPa (40 thousands of pounds persquare inch (ksi) to about 120 ksi); a tensile strength of 552 MPa (80ksi) is typical; and a preferred tensile strength of from about 414 MPa(60 ksi) to about 827 MPa (120 ksi). Polydioxanone, polycaprolactone,and polygluconate include tensile strengths of from about 103 MPa (15ksi) to about 414 MPa (60 ksi); a tensile strength of 241 MPa (35 ksi)is typical; and a preferred tensile strength of from about 172 MPa (25ksi) to about 310 MPa (45 ksi).

PLA, PLLA, PDLA and PGA have a tensile modulus of from about 2758 MPa to13790 MPa (400,000 pounds per square inch (psi) to about 2,000,000 psi);a tensile modulus of 6206 MPa (900,000 psi) is typical; and a preferredtensile modulus of from about 4827 MPa (700,000 psi) to about 8274 MPa(1,200,000 psi). Polydioxanone, polycaprolactone, and polygluconate havea tensile modulus of from about 1379 MPa (200,000 psi) to about 4827 MPa(700,000 psi); a tensile modulus of 3103 MPa (450,000 psi) is typical;and a preferred tensile modulus of from about 2413 MPa (350,000 psi) toabout 3792 MPa (550,000 psi).

The preferred design for the bioabsorbable structure of the stent-graftincludes 10-36 filaments braided into a tubular mesh configuration.Alternative designs could be made using more than 36 bioabsorbablefilament strands. Stent-grafts are envisioned having as many as 500filaments and which are made with braiders having sufficient carriercapacity.

Stents for arterial indications typically require high radial strengthto resist elastic recoil after PTA dilation of the muscular arterialwall tissue. The radial strength of a stent-graft can be increased byincreasing the number of filament strands in the design. Also the amountof open space in the stent mesh of the stent-grafts can be reduced byusing more filament strands. It may be desirable to utilize stents withless open space if there is concern that the endoprosthesis may becomeoccluded due to the ingrowth of tumorous tissue from cancer. A stentwith little open space could be used to purposely seal off branchvessels from the main artery. Larger diameter stent-grafts require morefilament strands in the braid to build the structural network over thelarger surface area. Large stent-grafts would be needed for the aortaand for the trachea and esophagus. Also, large stent-grafts could beused in the airway and esophagus to seal off fistulas or to prevent orlimit tissue ingrowth into the stent.

The present invention advantageously provides an improved scent-graftand a method for making and using such a stent-graft.

In sum, the invention relates to a stent-graft including a bioabsorbablestructural support including a tubular body having open ends, a sidewallstructure having openings therein, and an inside and an outside surfaceand a permanent graft having an inside and outside surface. One of thebioabsorbable structural support or the permanent graft cooperates withthe other and provides a coextensive portion wherein at least a part ofthe coextensive portion has a length of the bioabsorbable structuralsupport and a length of the permanent graft bonded or interbraidedtogether. The coextensive portion may be part or all of the longitudinallength of the stent-graft. The stent-graft may be adjustable between anominal state and a radially-reduced state. The tubular body may furtherinclude a plurality of bioabsorbable elements formed in a generallyelongated shape which is generally radially compressible andself-expandable. The stent-graft may provide an initial radial forcewhen implanted in a body lumen and the bioabsorbable structure portionbioabsorbs over time in-vivo with an eventual resulting decrease inradial force to the vessel wall, and the permanent graft portionsubstantially remains in the body lumen. The structural support and thepermanent graft may be bonded by adhesive means and the adhesive meansmay be bioabsorbable. The adhesive means may occupy a proximal and adistal end portion but not a mid portion over the coextensive portionwhich the structural support and graft are coextensive one another. Thebioabsorbable structural support may be made of at least one of poly(alpha-hydroxy acid), PGA, PLA, PLLA, PDLA, polycaprolactone,polydioxanone, polygluconate, polylactic acid-polyethylene oxidecopolymers, modified cellulose, collagen, poly(hydroxybutyrate),polyanhydride, polyphosphoester, poly(amino acids), or combinationsthereof and the graft may be made of at least one of PET, ePTFE, PCU, orPU. The elements may be substantially homogeneous in cross section andlength. The graft may include a plurality of interwoven fibers,mono-filaments, multi-filaments, or yarns. The graft may be a film,sheet, or tube. The graft may form a composite wall with body tissue inthe body lumen. The stent-graft may be permeated with body tissue andmay provide structural support to a body lumen for less than about 3years. The graft may be disposed on at least one of the inside andoutside surface of the structural support. The graft and the filamentsmay be interbraided. The bioabsorbable structural support may beannealed.

The invention also relates to a stent-graft including a tubular,radially compressible and self-expandable braided and annealed structurehaving a first set of filaments each of which extends in a helixconfiguration along a center line of the stent and having a first commondirection of winding. A second set of filaments each extend in a helixconfiguration along a center line of the stent and have a second commondirection of winding. The second set of filaments cross the first set offilaments at an axially directed angle. Each filament includesbioabsorbable material and has a substantially solid and substantiallyuniform cross-section, a tensile strength of from about 276 MPa (40 ksi)to about 827 MPa (120 ksi), a tensile modulus of from about 2758 MPa(400,000 psi) to about 13790 MPa (2,000,000 psi), and an averagediameter of from about 0.15 mm to about 0.6 mm. A permanent graftcooperates with at least a portion of the structure to form astent-graft adapted to be disposed in a body lumen. The graft mayconform with the structure. The first set and the second set may havethe same number of filaments. Each of the first and second sets offilaments may include from about 5 filaments to about 18 filaments. Theaxially directed angle when in a free radially expanded state afterbeing annealed but before being loaded on a delivery device may bebetween about 120 degrees and about 150 degrees.

The invention also relates to a method of making a stent-graft includingbraiding bioabsorbable filaments to form a tubular braid, the braidhaving a braid angle; disposing the braid on a mandrel; annealing thebraid at a temperature between about the bioabsorbable filament glasstransition temperature and about the melting point for a predeterminedtime to form an annealed stent; removing the stent from the mandrel, thestent having a filament crossing angle; providing a permanent graft; andadhering at least a portion of the graft to the annealed stent to forman assembly. The permanent graft may further comprise a braid angle andthe method may further include prior to the step of adhering matchingthe braid angle of the permanent graft to about the stent filamentcrossing angle. The method may further include prior to the step ofadhering, applying at least one of a thermoplastic adhesive, curableadhesive, and bioabsorbable polymer glue to the surface of the stent.The method may further include prior to the step of adhering, applyingradial compression or axial elongation to the assembly to apply pressureover at least a portion of the stent and graft. The braid may beannealed at a temperature of from about 60° C. to about 180° C. for aperiod of time of from about 5 minutes to about 120 minutes or annealedat a temperature of from about 130° C. to about 150° C. for a period oftime of from about 10 minutes to about 20 minutes.

The invention also relates to a method of making a stent-graft includingbraiding bioabsorbable elements to form a bioabsorbable tubular braid,the braid having a braid angle; providing a permanent graft film, sheet,or tube; disposing one of the permanent graft film, sheet, or tube orthe bioabsorbable tubular braid on a mandrel; disposing the other of thepermanent graft film, sheet, or tube or the bioabsorbable tubular braidover at least a portion of the other; adhering the permanent graft film,sheet, or tube to the braid to form a braid-graft; annealing thebraid-graft at a temperature between about the bioabsorbable elementsglass transition temperature and about the melting point for apredetermined time to form the stent-graft; and removing the stent-graftfrom the mandrel.

The graft film, sheet, or tube may include at least one of ePTFE and PCUand the bioabsorbable filament may include PLLA.

The invention also relates to a method of using a stent-graft includingproviding a tubular, radially self-expandable and radially compressible,axially flexible, braided and annealed structure comprising elongatebioabsorbable filaments. The filaments have a tensile strength of fromabout 276 MPa (40 ksi) to about 827 MPa (120 ksi), and a tensile modulusof from about 2758 MPa (400,000 psi) to about 13790 MPa (2,000,000 psi).Each filament has an average diameter of from about 0.15 mm to about 0.6mm; providing adhesive means; and providing a permanent graft disposedand adhered with the adhesive means to at least a portion of thestructure and forming a stent-graft assembly; deploying the stent-graftassembly into a body lumen at a treatment site; and allowing thestent-graft assembly to self-expand or expanding the stent-graftassembly in the body lumen. The bioabsorbable filaments may includePLLA, PDLA, PGA, or combinations thereof and the graft may include PET,ePTFE, PCU, or PU or combinations thereof.

The invention also relates to a method of using a stent-graft toregenerate a defective body vessel including disposing a stent-graftinto a body vessel having a vessel wall with a defect in the vesselwall, and natural tissue generation ability. The stent-graft includes abioabsorbable structure portion and a permanent graft portion and has anoutside surface. The bioabsorbable structure portion provides temporaryforce to the body vessel and the permanent graft portion provides apermanent synthetic wall at the area of the defect in the body vesseland is receptive to growth of the natural tissue therein and thereabout;placing the stent-graft in the vicinity of the defect such that at leasta portion of the stent-graft spans the defect in the vessel wall;providing contact between the outside surface of the stent-graft and thevessel wall whereby the stent-graft provides an initial radial force tothe vessel wall; and allowing or promoting healing at or around thestent-graft, the bioabsorbable structure portion adapted to bioabsorbover time in-vivo with an eventual resulting decrease in radial force tothe vessel wall, and the permanent graft portion adapted tosubstantially remain in the body lumen. The body vessel may be anartery. The permanent graft portion may be replaced over time by acomposite wall including natural tissue and the permanent graft portion.The defect may be at least one of an aneurysm, fistula, occlusivedisease, or recurrent occlusive disease. The defect may be substantiallyexcluded from the body vessel by one of the stent-graft or the compositevessel wall.

Bioabsorbable resins such as PLLA, PDLA, and PGA are available fromPURAC America, Inc. of Lincolnshire, Ill. Partially oriented yarns andflat yarns are commercially available from Wellman Inc. of Charlotte,N.C. The partially oriented yarns can be textured by Milliken, Inc. ofSpartenburg, S.C. Silicone adhesive is commercially available fromApplied Silicone of Ventura, Calif. The remaining materials discussed inthe application are commercially available.

Still other objects and advantages of the present invention and methodsof construction and use of the same will become readily apparent tothose skilled in the art from the following detailed description,wherein only the preferred embodiments are shown and described, simplyby way of illustration of the best mode contemplated of carrying out theinvention. As will be realized, the invention is capable of other anddifferent embodiments and methods of construction and use, and itsseveral details are capable of modification in various obvious respects,all without departing from the invention. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a stent-graft illustrating an exposedportion of the braided bioabsorbable filaments;

FIG. 2 is a side view of another embodiment of the stent-graftillustrating the graft disposed on a portion of the braided filaments;

FIGS. 3 a-3 d are various embodiments of the stent-graft in anunconstrained, radially expanded state taken through 3-3 of FIG. 2illustrating the graft disposed on the outside of the stent,interbraided or interwoven through the stent filaments, on the inside ofthe stent, and on both the inside and the outside stent, respectively.

FIG. 3 e is a side view of FIG. 3 d illustrating the stent-graft;

FIG. 4 is an isometric view of the bioabsorbable structure of thestent-graft;

FIG. 5 is a partial longitudinal cross-sectional view of thebioabsorbable structure of the stent-graft;

FIG. 6 is a side view of a second embodiment of the stent-graft;

FIG. 7 is an end view of the stent-graft shown in FIG. 6;

FIG. 8 is an isometric view of one of the filaments of the bioabsorbablestructure;

FIG. 9 is a cross-sectional view of one of the filaments of abioabsorbable structure;

FIGS. 10 a-10 f are side views of embodiments of filaments havingreservoir portions;

FIG. 11 is a cross-sectional view of a mono-filament strand of apermanent graft;

FIG. 12 is a cross-sectional view of a multi-filament yarn used informing a permanent graft;

FIG. 13 is a side elevation of a segment of the yarn;

FIGS. 14 a-14 d are side view of embodiments of permanent grafts;

FIG. 15 is a side view of a stent-graft in an unconstrained, radiallyexpanded state;

FIGS. 16 a-16 b are enlarged views of embodiments of grafts, showing theinterbraiding of several textile strands;

FIGS. 17A-17G schematically illustrate fabrication of a stent-graft;

FIGS. 18A-18F schematically illustrate fabrication of a stent-graft;

FIGS. 19A-19D schematically illustrate fabrication of a stent-graft;

FIGS. 20A-20F schematically illustrate fabrication of a stent-graft;

FIG. 21 illustrates an alternative stent-graft with localized bonding ofa bioabsorbable stent and a permanent graft;

FIG. 22 shows a further alternative stent-graft with selectivelypositioned grafts;

FIGS. 23-26 are side views of the stent-graft function in vivo over timeat a treatment site; and

FIG. 27 is a side elevation, partially in, section, showing astent-graft contained within a deployment device; and

FIG. 28 illustrates a stent-graft mounted on an alternative deploymentdevice.

DETAILED DESCRIPTION OF THE INVENTION

A stent-graft 100 is shown generally in FIG. 1 with a permanent graft(graft) 120 covering substantially all of a bioabsorbable structuralsupport (stent) 110 except an exposed portion which is shown uncoveredfor illustration purposes. An alternative embodiment of the stent-graft100 is illustrated generally in FIG. 2 where the filaments 112 areexposed at each end and are not covered by the graft.

The support function of the bioabsorbable stent 110 portion of thestent-graft 100 is temporary while the function of the graft 120 isgenerally permanent. For example, after bracing the lumen open for aperiod of time necessary for tissue formation on and within thestent-graft 100, the stent 110 is gradually absorbed and vesselcompliance and functional stresses are generally transferred to the newtissue. After implantation, the bioabsorbable stent 110 bioabsorbs overtime and the generally compliant graft 120 and natural tissue remain inthe vessel at the treatment site and form a composite vessel wall.

The stent 110 is formed from helically wound elongated filaments 112 andis preferably made of a non-toxic bioabsorbable polymer such as PGA,PLA, polycaprolactone, or polydioxanone, and the graft 120 is preferablymade of braided or film PET, ePTFE, PCU, or PU.

The graft 120 is made of braided or interwoven material formed fromfibers, strands, yarns, mono-filaments, or multi-filaments and isadhered with an adhesive to at least a portion of the stent 110. Thegraft 120 may also be formed from film, sheet, or tube. The especiallypreferred materials for the stent-graft 100 are PLLA for thebioabsorbable stent 110 and PET, PCU, or PU for the permanent graft 120.

Reference is made to FIGS. 3 a-3 e illustrating various embodiments ofthe stent-graft 100. The graft 120 is preferably disposed on the insidesurface of the bioabsorbable stent 110 as shown in FIG. 3 c. However,the graft 120 may be attached to the outside of the bioabsorbable stent110 as shown in FIG. 3 a or the graft elements 144, 145 may beinterbraided or woven with the stent filaments 112 as, for example,shown in FIG. 3 b. Alternatively, the graft 120 may be disposed on theinside surface and the outside surface of the bioabsorbable stent 110 asshown in FIG. 3 d. FIG. 3 e illustrates the stent-graft 100 with acut-out showing both interior and exterior grafts 120.

The graft 120 and the stent 110 are adhered together at predeterminedoverlapping locations using an adhesive 130. The stent-graft 100 may beadvantageously used for the treatment of arterial fistulas andaneurysms.

Additional detailed descriptions of the components of the stent-graft100 and methods of making and use are described in further detail below.

A. The Bioabsorbable Structural Support

Reference is made to FIGS. 4 and 5 showing the bioabsorbable structuralsupport (stent) 110 of the stent-graft 100. Stent 110 is made of aplurality of individually rigid, but, flexible and elastic filaments112, each of which extends in a helix configuration along a longitudinalcenter line of the body as a common axis. The filaments 112 define aradially self-expanding body. The sets of filaments 112 are interwovenin an over and under braided configuration intersecting at points suchas 114 to form an open mesh or weave construction. The stent 110 maybemade with a first number of filaments 112 having a common direction ofwinding but axially displaced relative to each other, and crossing asecond number of filaments 112 also axially displaced relative to eachother but having an opposite direction of winding. FIG. 4 shows a stent110 made of individual braided strands. FIG. 5 shows a stent 110 made ofpaired interbraided strands.

For reference and descriptive purposes, a braid becomes a stent 110after annealing. Annealing of the braid relaxes the stresses in thefilaments and sets the shape of the stent 110. The term “braid angle”refers to the included angle between interbraided filaments of the braidin the axial orientation prior to annealing and the term “filamentcrossing angle” refers to the included angle of the stent afterannealing.

The stent 110 may be made into various shapes, for example, as shown inFIGS. 6 and 7 where one end tapers and has a diameter which decreases insize. A tapered filament structure may be utilized as an intravascularfilter or occlusion device.

Reference is made to FIG. 8 which shows a portion of a typical filament112 which makes up a stent 110. Stent 110 is shown in its expanded statewhen subject to no external loads or stresses. The filaments 112 areresilient, permitting the radial compression of stent 110 into areduced-radius, extended-length configuration suitable for deliverytransluminally to the desired treatment site. FIG. 9 illustrates across-sectional view of one embodiment of the bioabsorbable filaments112. As shown, the filaments 112 are substantially homogeneous in crosssection.

As described in greater detail below, at least one and preferably allfilaments 112 include one or more commercially available grades ofpolylactide, poly-L-lactide (PLLA), poly-D-lactide (PDLA), polyglycolide(PGA), polydioxanone, polycaprolactone, polygluconate, polylacticacid-polyethylene oxide copolymers, modified cellulose, collagen,poly(hydroxybutyrate), polyanhydride, polyphosphoester, poly(aminoacids), poly(alpha-hydroxy acid) or related copolymers materials.

A bioabsorbable stent is disclosed in U.S. patent application entitled“Bioabsorbable Self-Expanding Stent”, Ser. No. 08/904,467, filed Aug. 1,1997 (now U.S. Pat. No. 6,245,103). Another bioabsorbable stent isdisclosed in U.S. patent application entitled “Bioabsorbable ImplantableEndoprosthesis With Reservoir And Method Of Using Same,” Ser. No.08/905,806, filed Aug. 1, 1997 (now U.S. Pat. No. 5,980,564).

A stent 110 may be made by braiding between 10-36 independent strands of0.15-0.60 mm diameter bioabsorbable polymeric filament 112 interwoveninto helical shape strands on a round bar mandrel of 3-30 mm diameter.One-half of the number of helical strands are wound clockwise andone-half are wound counterclockwise such that each clockwise helicalstrand is adjacent and interbraided with a counterclockwise strand. Thetubular braid is made with strand braid angle of about 120-150 degreesand a pitch angle (angle between a filament and transverse axis of thestent) of about 15-30 degrees while on the braid bar mandrel.

The braid is slid off of the braid bar and onto a 0.2-10 mm smallerdiameter annealing bar or tube mandrel. Each end of the braid is pulledor compressed to cause axial extension or compression of the braid onthe anneal mandrel, or left free. Each end of the braid is secured oneach end of the anneal mandrel to fix the preset axial position of thebraid, or left free. The braid is annealed on the anneal mandrel at atemperature between the glass-transition temperature and meltingtemperature of the bioabsorbable polymer for about 5-120 minutes in air,vacuum, or an inert atmosphere. The stent 110 is cooled on the annealmandrel to about room temperature, slid off of the anneal mandrel, andcut to a desired length.

In addition to substantially solid and homogenous filaments 112, otherembodiments of filaments 112 as shown in FIGS. 10 a-10 f and having oneor more reservoir portions including hollow 22, cavity 32, porous 42portions, or combinations thereof can be used. The term “reservoir” isreferred to as a volume of space internal to the filament outer surfacewhere polymer degradation by-products accumulate. The reservoir mayinclude both internal and external passages, with the external passagesopening through an outside wall or end of the filament 112. FIG. 10 aillustrates a hollow filament 112 with a center core; FIG. 10 billustrates a filament 112 having at least one cavity with sealed ends;FIG. 10 c illustrates a filament 112 having at least one pore (internalor external porosity, or both); FIG. 10 d illustrates a multi-lumenfilament 112 with a plurality of hollow portions; FIG. 10 e illustratesa cross-section of a filament 112 having a plurality of internal pores;FIG. 10 f illustrates a filament 112 having a plurality of surfacepores. The external pores may connect with internal pores, cavities, orhollow portions. The reservoir portions have a size greater than about 1micron and have a volume percentage greater than about 10%.

Although degradation occurs throughout the filament 112, the rate ofdegradation is generally higher at locations having a lower pH as acidicenvironments catalyze degradation. By-products from degradation such aslactic acid or glycolic acid are stored or accumulate in the reservoirportions which accelerate degradation of the inner surfaces.

Table I describes various preferred reservoir embodiments of filament112.

TABLE I % % Volume Type of Volume Hollow or Hollow or Cavity FeaturesReservoir: Solid Cavity Dimensions axial core (one 65-90 10-35 Ø < 50%of O.D. x length of lumen tubing) filament strand multi-lumen 50-9010-40 Ø < 50% of O.D./# of lumens, filament (two or length of filamentstrand more lumens) internal porosity 70-90 10-30 1-20 microns externalporosity 80-90 10-20 1-20 microns (surface oriented)

The degradation by-products in the reservoir portions may have anaverage pH level which decreases over time in vivo. The average pH levelin the reservoir may be between about 3 and 7. The endoprosthesis maysubstantially degrade in vivo in less than 3 years. The filaments maycomprise PLLA, PDLA, or combinations thereof and substantially degradein vivo in from about 1 year to about 2 years. The filaments maycomprise polylactide, polyglycolide, or combinations thereof andsubstantially degrade in vivo in from about 3 months to about 1 year.The filaments may comprise polyglycolide, polygluconate, polydioxanone,or combinations thereof and substantially degrade in vivo in from about1 week to about 3 months.

The filaments 112 may have an outer surface containing a multitude ofempty pores which have an average depth of at least about 0.5 micron.The elongate filament 112 prior to implantation may contain at least oneempty internal cavity which does not open to the filament 112 outersurface. The average cavity cross-sectional area is from about 2 toabout 40 percent of the average filament 112 cross-sectional area.

Tables II and III show various embodiments of the bioabsorbable stent110 of the stent-graft 100.

TABLE II # of Filament Brand Mandrel Braid Angle, PLLA Diameter PDLADiameter, PLLA/PDLA PGA Diameter, Strands in Stent Diameter, mm Degreesmm mm Diameter, mm mm 10 3-6 120-150 .15-.25 .15-.25 .15-.25 .20-.30 103-6 120-150 .20-.30 .20-.30 .20-.30 .25-.35 12 3-8 120-150 .20-.30.20-.30 .20-.30 .25-.35 12 3-8 120-150 .35-.45 .35-.45 .35-.45 .40-.5015  6-10 120-150 .30-.40 .30-.40 .30-.40 .35-.45 15  6-10 120-150.35-.45 .35-.45 .35-.45 :40-.50 18  7-12 120-150 .35-.45 .35-.45 .35-.45.40-.50 18  7-12 120-150 .40-.50 .40-.50 .40-.50 .45-.55 20 3-9 120-150.20-.30 .20-.30 .20-.30 .25-.35 24  8-12 120-150 .20-.30 .20-.30 .20-.30.25-.35 24  9-14 120-150 .25-.35 .25-.35 .25-.35 .30-.40 24 12-18120-150 .30-.40 .30-.40 .30-.40 .35-.45 30 16-26 120-150 .30-.40 .30-.40.30-.40 .35-.45 36 20-30 120-150 .35-.45 .35-.45 .35-.45 .40-.50 2414-20 120-150 .35-.45 .35-.45 .35-.45 .40-.50

TABLE III PGA/ # of Filament Braid PGA/ trimethylene Strands in MandrelBraid Angle, PGA/PLLA polycaprolactone Polydioxanone carbonate BraidDiameter, mm Degrees Diameter, mm diameter, mm diameter, mm diameter, mm10 3-6 120-150 .20-.30 .22-.32 .25-.35 .22-.32 10 3-6 120-150 .25-.35.27-.37 .30-.40 .27-.37 12 3-8 120-150 .25-.35 .27-.37 .30-.40 .27-.3712 3-8 120-150 .40-.50 .42-.52 .45-.55 .42-.52 15  6-10 120-150 .35-.45.37-.47 .40-.50 .37-.47 15  6-10 120-150 .40-.50 .42-.52 .45-.55 .42-.5218  7-12 120-150 .40-.50 .42-.52 .45-.55 .42-.52 18  7-12 120-150.45-.55 .47-.57 .50-.60 .47-.57 20 3-9 120-150 .25-.35 .27-.37 .30-.40.27-.37 24  8-12 120-150 .25-.35 .27-.37 .30-.40 .27-.37 24  9-14120-150 .30-.40 .32-.42 .35-.45 .32-.42 24 12-18 120-150 .35-.45 .37-.47.40-.50 .37-.47 30 16-26 120-150 .35-.45 .37-.47 .40-.50 .37-.47 3620-30 120-150 .40-.50 .42-.52 .45-.55 .42-.52 24 14-20 120-150 .40-.50.42-.52 .45-.55 .42-.52

A separately manufactured and permanent graft 120 is disposed on andadhered to a portion of the stent 110 with an adhesive to form thestent-graft 100 and is discussed in further detail below.

B. The Permanent Graft

The permanent graft 120 generally radially expands and contracts withthe bioabsorbable stent 110. Vascular grafts are shown, for example, inU.S. Pat. No. 5,116,360.

Reference is made to FIG. 11 which shows a cross-section of amonofilament strand 144 which makes up a graft 120. Strands can bewoven, braided, or knitted into a tubular fabric shape. FIG. 12 shows across-section of a multi-filament yarn 145. FIG. 13 shows the yarn 145of FIG. 12 in a side elevation with a twist orientation. Additionally,the graft 120 may include extruded or drawn tubes, films, or sheets. Thegraft 120 may include layers to make a composite structure withoptimized porosity and mechanical properties.

Reference is made to FIGS. 14 a-14 d showing various embodiments ofgraft 120. FIG. 14 a shows a tubular graft 120, preferably made of PET;FIG. 14 b shows a tubular graft 120, preferably made of extruded ePTFE,PCU, or PU; FIG. 14 c shows an ePTFE, PCU or PU film or sheet preferablyformed in the shape of a tubular graft 120 with a butt joint oroverlapping joint 121 as shown in FIG. 14 d.

FIG. 15 shows a stent-graft 100 with exposed filament end portions 46and 48 which are used to facilitate long-term fixation of thestent-graft 100 ends with the vessel wall. FIGS. 16 a-b show an exteriorlayer of stent-graft 100 as a textile sheeting or graft 120, formed ofmultiple textile strands 42 and interwoven with one another. The textilestrands 42 are shown braided in two embodiments in FIGS. 16 a and 16 b.Other embodiments and patterns may also be used. The textile strands 42intersect one another to define a braid angle θ in a nominal state.FIGS. 15 and 16 show a filament crossing angle a on stent 110 and aangle θ on graft 120 which bisects a longitudinal axis 38.

Textile strands 42 preferably are multi-filament yarns, although theymay be mono-filaments. In either case, the textile strands are finerthan the structural strands, and range from about 10 denier to 400denier. Individual filaments of the multi-filament yarns can range fromabout 0.25 to about 10 denier.

To form graft 120, the strands or yarns may be interbraided on a mandrelsuch that they intersect each other and form a braid angle. The numberof strands or yarns can range from 20 to 700. The graft 120 ispreferably made of PET (Dacron) or polycarbonate urethane (PCU) such asCorethane™, however, other materials may include polypropylene (such asSpectra), polyurethane, HDPE, polyethylene, silicone, PTFE, polyolefins,and ePTFE.

The multi-filament yarns are thermally set in generally the same manneras the bioabsorbable stent 110. After the graft 120 is thermally set, itis removed from the mandrel and washed ultrasonically or by agitation.The graft 120 is then cut to a desired length using a laser, which fusesthe ends of the strands to prevent unraveling.

One preferred graft and method of making the same is a braided textiletubular sleeve that is adjustable between a nominal state and aradially-reduced axially-elongated state as described in U.S. patentapplication entitled “Stent Graft With Braided Polymeric Sleeve”, Ser.No. 08/946,906 filed Oct. 8, 1997 (now U.S. Pat. No. 5,957,974) whichclaims the benefit of U.S. Provisional Application Ser. No. 60/036,160,filed Jan. 23, 1997. A device having a flexible tubular liner isdisclosed in U.S. Pat. No. 4,681,110. Several composite braidedstructures are shown in International Patent Publications Nos. WO91/10766; WO 92/16166; WO 94/06372; and WO 94/06373. Additional examplesare disclosed in U.S. Pat. Nos. 4,475,972; 4,738,740; and 5,653,747.Other examples are disclosed in U.S. patent application Ser. No.08/640,062 (now U.S. Pat. No. 5,758,562) and U.S. patent applicationSer. No 08/640,091 (now U.S. Pat. No. 5,718,159), both filed Apr. 30,1996 and assigned to the assignee of this application. The graft 120 maybe formed of an expandable uniaxially or biaxially orientedpolytetrafluoroethylene tube having a microstructure of nodules andfibrils as described in EP 0 775 472 A2.

Table IV illustrates several examples of braided textile fabric graftshaving strands with a packing factor of 0.54, and, preferably, a braidangle of about 110 degrees. A coating can be applied to the yarn toenhance surface properties of the yarn and reduce friction.

TABLE IV Inner # of Yarn Fabric Yarn Fabric Yarn Diameter, Yarn LinearThickness, Coverage, Porosity, Aspect mm Ends Density inch % % Ratio 672 70 .0031 98 55 6.53 6 96 50 .0032 97 58 4.62 6 120 40 .0034 94 623.15 6 144 30 .0032 93 64 2.69 12 192 50 .0032 97 58 4.62 24 352 60.0035 97 58 4.56 40 512 70 .0034 98 56 5.45

Adhesives 130 and methods of manufacturing the stent-graft 100 arediscussed in further detail below.

C. Bonding the Graft to the Bioabsorbable Structural Support

A variety of methods and adhesives 130 may be used for bonding the graft120 to the bioabsorbable structural support 110 are possible. Themethods below reference PLLA material, however, other bioabsorbablematerials may be used accordingly. A siloxane polymer (silicone) may beused as an adhesive. Other alternative polymers may includefluorosilicone and polycarbonate urethane.

Method 1

A first method includes application of a thermoplastic adhesive to thesurface of the PLLA braid by spraying the PLLA braid with a solution ofpolyurethane or thermoplastic adhesive dissolved in an organic solvent.The graft is disposed over a mandrel and the stent is disposed over thegraft. The assembly is heated in an oven at a temperature above thesoftening temperature of the thermoplastic adhesive and below themelting point of PLLA. The PLLA braid will shrink to the diameter of themandrel, and make intimate contact with the graft and bond to the graft.The PLLA braid is preferably made such that the braid angle aboutmatches the braid angle of the graft. Adhesives include thepolycarbonate urethanes disclosed in U.S. Pat. No. 5,229,431.

Preferred Steps of Method 1

-   1. Affix the ends of the stent in a fixture which rotates the stent    about its central axis.-   2. Spray the stent with a 7.5% solids solution of 2.5W30    polycarbonate urethane, such as Corethane™, in DMA. Spray using an    airbrush with a 7 cc spray-cup. Spray from a distance of 20-25    centimeters (cm) (8-10 inches) from the stent surface, using a    reciprocating motion so as to evenly coat the stent surface.-   3. When the spray cup is empty, heat the stent to a temperature    above the flashpoint of DMA and below the glass transition    temperature of the PLLA. Heat for 5-20 minutes, preferably 10    minutes.-   4. Repeat step 2.-   5. Repeat step 3.-   6. Remove the stent from the fixture and cut off the ends of the    stent which were used for gripping and were not sprayed.-   7. Place a section of braided PET graft over a mandrel (For example,    place 6 mm diameter graft on a 6 mm mandrel).-   8. Place the sprayed stent over the mandrel and graft.-   9. Affix the ends of the stent to the mandrel, such that the pitch    length of the stent matches that of the graft.-   10. Place the mandrel/graft/stent in an oven at 120°-165° C. for    5-120 minutes, preferably 165° C. for 20 minutes.

Method 2

A second method includes braiding extruded PLLA filaments to form atubular interwoven braid and annealing the braid to the desired braidangle and diameter. Apply a thermoplastic adhesive to the surface of thePLLA mesh. Dispose the braid and graft on a mandrel such that, the graftis on the interior and/or exterior of the braid. Apply radialcompression or axial elongation to the composite to create intimatecontact between the layers. One preferred method of applying radialcompression to the structure uses fluorinated ethylene propylene (FEP)“heat-shrink” tubing which reduces in diameter when heated above itsglass transition temperature. Bond the composite layers by heating thestructure to a temperature above the glass transition temperature of theheat shrink tubing, and below the melting point of the PLLA filaments.

Preferred Steps of Method 2

-   1. Braid the PLLA mesh.-   2. Anneal the mesh to the desired diameter and braid angle by one of    the previously described methods.-   3. Affix the ends of the stent in a fixture which rotates the stent    about its central axis.-   4. Spray the stent with a 7.5% solids solution of 2.5W30    polycarbonate urethane, such as Corethane™, in DMA. Spray using an    airbrush with a 7 cc spray-cup. Spray from a distance of 20-25 cm    (8-10 inches) from the stent surface, using a reciprocating motion    so as to evenly coat the stent surface.-   5. When the spray-cup is empty, heat the stent to a temperature    above the flashpoint of DMA and below the glass transition    temperature of the PLLA. Heat for 5-20 minutes, preferably 10    minutes.-   6. Repeat step 4.-   7. Repeat step 5.-   8. Place a graft which has the same braid angle as the stent over or    under the stent.-   9. Place the stent and graft over a mandrel which matches the ID of    the stent, preferably a fluoropolymer-coated stainless steel    mandrel.-   10. Place a piece of FEP heat shrink tubing over the mandrel and    stent/graft so that the heat shrink covers the stent and graft.-   11. Heat the assembly in an oven at 120°-165° C. for 5-120 minutes,    preferably 165° C. for 20 minutes-   12. Remove the heat shrink from the mandrel, and remove the    stent-graft from the mandrel.

Method 3

A third method includes braiding extruded PLLA filaments to form atubular interwoven braid, and anneal the braid to the desired braidangle and diameter. Apply a coating of curable adhesive to the surfaceof the braid. Disposing the graft on the interior and/or exterior of thebraid such that at least a portion of the graft is in contact with thecurable adhesive. Heat the composite at a temperature between the curetemperature of the curable adhesive and the glass transition temperatureof the PLLA braid.

Preferred Steps of Method 3

-   1. Braid the PLLA filaments into a braid.-   2. Anneal the braid to the desired diameter and braid angle by one    of the previously described methods.-   3. Affix the ends of the stent in a fixture which rotates the stent    about its central axis.-   4. Spray the stent with a 6% solids solution of silicone such as    Applied Silicone 40,000 in THE and xylene. Spray using an airbrush    or atomizer. The spray can be applied either to the ends of the    stent or to the total stent length. Apply silicone until the desired    thickness is obtained.-   5. Apply a stent to the inside and/or outside of the stent so that    the graft contacts the silicone adhesive.-   6. Place the stent and graft into an oven at 120°-165° C. for 5-120    minutes, preferably 150° C. for 30 minutes.

Method 4

A fourth method includes braiding extruded PLLA filaments to form atubular interwoven braid, and annealing the braid to the desired braidangle and diameter. Apply a coating of a bioabsorbable polymer “glue” tothe surface of the braid by dissolving poly(d-lactide), PDLA in asolvent such as dimethylformamide (DMF), and spray the solution on tothe stent. While the polymer “glue” is tacky, place the graft on theinterior and/or exterior of the mesh so that all layers of the compositeare in contact. Bond the braid to the graft by heating the structure toa temperature above the flash point of the polymer “glue” solvent andbelow the glass transition temperature of the PLLA braid. This methodmay also utilize heat shrink as provided in the second method.

Preferred Steps of Method 4

-   1. Braid the PLLA filaments into a braid.-   2. Anneal the braid to the desired diameter and braid angle by one    of the previously described methods.-   3. Affix the ends of the stent in a fixture which rotates the stent    about its central axis.-   4. Spray the stent with a 7.5% solids solution of PDLA in DMF. Spray    using an airbrush or atomizer. The spray can be applied either to    the ends of the stent or to the total stent length. Apply PDLA until    the desired thickness is obtained.-   5. Apply a stent to the inside and/or outside of the stent so that    the graft contacts the silicone adhesive.-   6. Place the stent and graft into an oven at 60°-100° C. for 5-120    minutes, preferably 85° C. for 20 minutes.

Method 5

A fifth method includes braiding extruded PLLA filaments to form atubular interwoven braid, and annealing the braid to the desired braidangle and diameter. Apply a coating of a bioabsorbable polymer “glue” tothe surface of the braid. Placing the graft on the interior and/orexterior of the braid. Bond the braid to the graft by heating thestructure to a temperature above the melting point of the polymer “glue”and below the glass transition temperature of the PLLA braid. Thismethod may also utilize heat shrink as provided in the second method.

Preferred Steps of Method 5

-   1. Braid the PLLA filaments into a braid.-   2. Anneal the braid to the desired diameter and braid angle by one    of the previously described methods.-   3. Affix the ends of the stent in a fixture which rotates the stent    about its central axis.-   4. Spray the stent with a 7.5% solids solution of PGA in a solvent.    Spray using an airbrush with a 7 cc cup. Spray from a distance of    20-25 cm (8-10 inches) from the stent surface, using a reciprocating    motion so as to evenly coat the stent surface.-   5. When the spray-cup is empty, heat the stent to a temperature    above the flashpoint of the solvent and below the glass transition    temperature of the PGA. Heat for 5-30 minutes, preferably 10    minutes.-   6. Repeat step 4.-   7. Repeat step 5.-   8. Place a graft which has the same braid angle as the stent over or    under the stent.-   9. Place the stent and graft over a mandrel which matches the ID of    the stent, preferably a fluoropolymer-coated stainless steel    mandrel.-   10. Place a piece of FEP heat shrink tubing over the mandrel and    stent/graft so that the heat shrink covers the stent and graft.-   11. Heat the assembly in an oven at 120°-165° C. for 5-120 minutes,    preferably 165° C. for 20 minutes.-   12. Remove the heat shrink from the mandrel, and remove the    stent-graft from the mandrel.    D. Methods of Making a Stent-Graft

A first method is shown in FIGS. 17A-17G. The steps include providingextruded PLLA filament as shown in FIG. 17A. FIG. 17B shows braiding ofextruded filaments to form a tubular interwoven braid. FIG. 17C showsthe braid off the mandrel with a braid angle from about 120 to 150degrees and a diameter of about 11 mm. FIG. 17D shows a straight tubularanneal mandrel, preferably with about a 9 mm diameter. FIG. 17E showsthe braid being axially compressed in the anneal mandrel to a diameterof about 11.5 mm. The braid is annealed at a temperature between theglass transition temperature and melting point of the bioabsorbable PLLAfilament for 15 minutes in a recirculating air oven. The braid willshrink onto the surface of the mandrel during the annealing cycle. Thebraid can be designed to shrink to a desired diameter and desiredfilament crossing angle. FIG. 17F shows the annealed stent off theanneal mandrel with a filament crossing angle from about 130 to 150degrees. As shown in FIG. 17G, the graft is adhered to the annealedstent using a bioabsorbable adhesive while matching within about plus orminus 5° of the graft braid angle to the annealed stent filamentcrossing angle.

A second method is shown in FIGS. 18A-18F. The steps include providingextruded PLLA filament as shown in FIG. 18A. FIG. 18B shows braiding ofextruded filaments to form a tubular interwoven braid. FIG. 18C showsthe braid off the mandrel with a braid angle from about 120 to 150degrees and a diameter of about 11 mm. FIG. 18D shows a straight tubularanneal mandrel, preferably with about a 9 mm diameter. FIG. 18E showsthe braid and graft being axially compressed in the anneal mandrel to adiameter of about 11.5 mm and being adhered together using abioabsorbable adhesive while matching within about plus or minus 5° ofthe graft braid angle to about the braid angle. The braid-graft isannealed at a temperature between the glass transition temperature andmelting point of the bioabsorbable PLLA filament for 15 minutes in arecirculating air oven. The braid-graft will shrink onto the surface ofthe mandrel during the annealing cycle. The braid-graft can be designedto shrink to a desired diameter and filament crossing angle. FIG. 18Fshows the annealed stent-graft off the anneal mandrel with a filamentcrossing angle from about 130 to 150 degrees.

A third method is shown in FIGS. 19A-19D. The steps include providingextruded PLLA filament as shown in FIG. 19A and annealing unconstrainedPLLA filaments at a temperature between the glass transition temperatureand the melting point for 15 minutes in a recirculating air oven. FIG.19B shows braiding of extruded annealed filaments to form a tubularinterwoven braid. FIG. 19C shows the stent off the mandrel with afilament crossing angle from about 120 to 150 degrees and a diameter ofabout 10 mm. FIG. 19D shows the stent and graft being adhered togetherusing a bioabsorbable adhesive while matching within about ±5° the graftbraid angle to about the filament crossing angle.

A fourth method is shown in FIGS. 20A-20F. The steps include providingextruded PLLA filament and graft fiber as shown in FIG. 20A. FIG. 20Bshows co-braiding of extruded filaments and graft to form a tubularinterwoven braid-graft. FIG. 20C shows the braid-graft off the mandrelwith a braid angle from about 120 to 150 degrees and a diameter of about11 mm. FIG. 20D shows a straight tubular anneal mandrel, preferably withabout a 9 mm diameter. FIG. 20E shows the braid-graft being axiallycompressed on the anneal mandrel to a diameter of about 11.5 mm. FIG.20F shows the braid-graft is annealed at a temperature between the glasstransition temperature and melting point of the bioabsorbable PLLAfilament for 15 minutes in a recirculating air oven. The braid-graftwill shrink onto the surface of the mandrel during the annealing cycle.The braid-graft can be designed to shrink to a desired diameter andfilament crossing angle. The annealed stent-graft is removed from theanneal mandrel with a filament crossing angle from about 130 to 150degrees and a diameter of about 10 mm. The interbraiding of PLLAfilaments and graft material forms an interwoven tubular mesh with adesired porosity.

E. Stent-Grafts

The graft 120 may surround the outside surface of stent 110 or the stent110 may surround the outside surface of graft 120. In anotherembodiment, two grafts 120 may be used to surround and sandwich thestent 110. The filament crossing angle of the assembly generallydetermines the relationship between radial compression and axialelongation of the stent-graft 100. Smaller angles generally result inless axial shortening for a given amount of radial enlargement. Thegraft 120 is highly compliant and conforms to changes in the shape ofthe stent 110.

A primary consideration is to select a braid angle 0 of the graft 120with respect to a braid angle a of the stent 110, and to closely matchthe geometrical diameter and elongation properties of the stent 110 andgraft 120 formed into the stent-graft 100 by about matching therespective braid angles.

FIG. 21 shows a stent-graft 100 with portions of exposed ends 100A and100B of the stent 110 coated with adhesive 130. Bond regions 120A and120B have axial lengths, preferably of about 17 mm, where the stent 110and graft 120 are coated with adhesive 130 and bonded together. Over amedial region 120C, the graft 120 and stent 110 are adjacent one anotherand in surface contact, but not bonded.

FIG. 22 shows a stent-graft 100 with a stent 110 surrounded by proximaland distal grafts 120. The stent 110 is exposed at stent-graft endportions 110A, 110B. Each of the grafts 120 is positionable along anintraluminal location where shunting of the blood flow is desired.

An exposed medial region 110C between grafts 120 is positionable inalignment with a branch of the vessel being treated, so that stent-graft100 can provide the intended shunting without blocking flow between themain vessel and the branch between the two shunting areas.

FIG. 23 shows an artery lumen 150, artery wall 155 and an untreatedarterial aneurysm 160. FIGS. 24-26 schematically show the stent-graft100 as it is intended to function in-vivo at a treatment site, forexample, an aneurysm. FIG. 24 shows a stent-graft 100 implanted in aartery lumen 150 and within or over an aneurysm 160. FIG. 25 showshealing occurring around the stent-graft 100 with exclusion of theaneurysm 160. FIG. 26 shows the bioabsorbable stent 110 has absorbed andthat the graft 120 remains in the artery lumen 150 and has becomeincorporated in the artery wall 155.

Stent-graft 100 offers considerable advantages. In particular, thepolymers from which it is formed are highly biocompatible and exhibitgood resistance to thrombosis and bacteria adhesion.

EXAMPLE 1

Stent-graft 100 can be fabricated from a stent 110 having 10 filamentstrands of 0.15-0.25 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.20-0.30 mm diameter PGA, PGA-PLLA copolymer, 022-0.32 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.25-0.35 mm diameter polydioxanone on a 3-6 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 6 French in size.

EXAMPLE 2

Stent-graft 100 can be fabricated from a stent 110 having 10 filamentstrands of 0.20-0.30 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.25-0.35 mm diameter PGA, PGA-PLLA copolymer, 0.27-0.37 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.30-0.40 mm diameter polydioxanone on a 3-6 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 8 French in size.

EXAMPLE 3

Stent-graft 100 can be fabricated from a stent 110 having 12 filamentstrands of 0.20-0.30 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.25-0.35 mm diameter PGA, PGA-PLLA copolymer, 0.27-0.37 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.30-0.40 mm diameter polydioxanone on a 3-8 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 8 French in size.

EXAMPLE 4

Stent-graft 100 can be fabricated from a stent 110 having 12 filamentstrands of 0.35-0.45 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.40-0.50 mm diameter PGA, PGA-PLLA copolymer, 0.42-0.52 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.45-0.55 mm diameter polydioxanone on a 3-8 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 11 French in size.

EXAMPLE 5

Stent-graft 100 can be fabricated from a stent 110 having 16 filamentstrands of 0.30-0.40 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.35-0.45 mm diameter PGA, PGA-PLLA copolymer, 0.37-0.47 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.40-0.50 mm diameter polydioxanone on a 6-10 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 9 French in size.

EXAMPLE 6

Stent-graft 100 can be fabricated from a stent 110 having 16 filamentstrands of 0.35-0.45 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.40-0.50 mm diameter PGA, PGA-PLLA copolymer, 0.42-0.52 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.45-0.55 mm diameter polydioxanone on a 6-10 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 11 French in size.

EXAMPLE 7

Stent-graft 100 can be fabricated from a stent 110 having 18 filamentstrands of 0.35-0.45 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.40-0.50 mm diameter PGA, PGA-PLLA copolymer, 0.42-0.52 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.45-0.55 mm diameter polydioxanone on a 7-12 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 11 French in size.

EXAMPLE 8

Stent-graft 100 can be fabricated from a stent 110 having 18 filamentstrands of 0.40-0.50 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.45-0.55 mm diameter PGA, PGA-PLLA copolymer, 0.47-0.57 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.50-0.60 mm diameter polydioxanone on a 7-12 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 13 French in size.

EXAMPLE 9

Stent-graft 100 can be fabricated from a stent 110 having 20 filamentstrands of 0.20-0.30 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.25-0.35 mm diameter PGA, PGA-PLLA copolymer, 0.27-0.37 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.30-0.40 mm diameter polydioxanone on a 3-9 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 8 French in size.

EXAMPLE 10

Stent-graft 100 can be fabricated from a stent 110 having 24 filamentstrands of 0.20-0.30 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.25-0.35 mm diameter PGA, PGA-PLLA copolymer, 0.27-0.37 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.30-0.40 mm diameter polydioxanone on a 8-12 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 9 French in size.

EXAMPLE 11

Stent-graft 100 can be fabricated from a stent 110 having 24 filamentstrands of 0.25-0.35 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.30-0.40 mm diameter PGA, PGA-PLLA copolymer, 0.32-0.42 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.35-0.45 mm diameter polydioxanone on a 9-14 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 11 French in size.

EXAMPLE 12

Stent-graft 100 can be fabricated from a stent 110 having 24 filamentstrands of 0.30-0.40 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.35-0.45 mm diameter PGA, PGA-PLLA copolymer, 0.37-0.47 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.40-0.50 mm diameter polydioxanone on a 12-18 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on mebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-3 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 12 French in size.

EXAMPLE 13

Stent-graft 100 can be fabricated from a stent 110 having 30 filamentstrands of 0.30-0.40 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.35-0.45 mm diameter PGA, PGA-PLLA copolymer, 0.37-0.47 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.40-0.50 mm diameter polydioxanone on a 16-26 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-6 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 15 French in size.

EXAMPLE 14

Stent-graft 100 can be fabricated from a stent 110 having 36 filamentstrands of 0.35-0.45 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.40-0.50 mm diameter PGA, PGA-PLLA copolymer, 0.42-0.52 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.45-0.55 mm diameter polydioxanone on a 20-30 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-6 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 19 French in size.

EXAMPLE 15

Stent-graft 100 can be fabricated from a stent 110 having 24 filamentstrands of 0.35-0.45 mm diameter PLLA, PDLA, PLLA-PDLA copolymer,0.40-0.50 mm diameter PGA, PGA-PLLA copolymer, 0.42-0.52 mm diameterPGA-polycaprolactone copolymer, PGA-trimethylcarbonate copolymer, or0.45-0.55 mm diameter polydioxanone on a 14-20 mm diameter braid mandrelwith a filament braid angle of 120-150 degrees while the braid is on thebraid mandrel. The braid is annealed on a bar or tube mandrel that hasan outer diameter 0.2-6 mm smaller than the braid mandrel diameter at atemperature between the polymer glass-transition temperature and themelting temperature for 5-120 minutes in air, vacuum, or inertatmosphere with the braid in an axially extended, free, or contractedposition. The stent is cooled to about room temperature, slid off theanneal mandrel, cut to the desired stent length, and adhered to a graft120 made of one of PET, ePTFE, PCU, or PU. The stent-graft 100 may beloaded onto a delivery system at least 15 French in size.

Annealed Stent Grant Braid Bioabsorbable Bioabsorbable Anneal AnnealedFilament Braid Graft Mandrel Bioabsorbable Filament Braid Mandrel StentCrossing mandrel Strands Graft Braid Dia., Strands Dia., Angle, Dia.,I.D., Angle, Dia., in Graft Yarn Angle, mm in Braid mm Deg. mm mm Deg.mm Braid Denier Deg. 8 24 0.25 130-135 6 6.0 105-115 6.5 120 40 105-11510 24 0.25 130-135 7 7.0 105-115 7.5 120 50 105-115 10 24 0.25 130-135 88.0 105-115 8.5 120 50 105-115 12 24 0.25 130-135 9 9.0 105-115 9.5 12060 105-115 12.5 24 0.25 130-135 10 10.0 105-115 10.5 192 40 105-115 1424 0.30 130-135 12 12.0 105-115 12.5 192 50 105-115 22 36 0.35 130-13520 20.0 105-115 20.5 352 40 105-115 25.8 36 0.40 130-135 22 22.0 105-11522.5 352 50 105-115 28 36 0.40 130-135 24 24.0 105-115 24.5 352 50105-115

TABLE VI Annealed Stent Grant Braid Bioabsorbable Bioabsorbable AnnealAnnealed Filament Braid Graft Mandrel Bioabsorbable Filament BraidMandrel Stent Crossing mandrel Strands Graft Braid Dia., Strands Dia.,Angle, Dia., I.D., Angle, Dia., in Graft Yarn Angle, mm in Braid mm Deg.mm mm Deg. mm Braid Denier Deg. 8 24 0.25 105-115 6 6.0 105-115 6.5 12040 105-115 10 24 0.25 105-115 7 7.0 105-115 7.5 120 50 105-115 10 240.25 105-115 8 8.0 105-115 8.5 120 50 105-115 12 24 0.25 105-115 9 9.0105-115 9.5 120 60 105-115 12.5 24 0.25 105-115 10 10.0 105-115 10.5 19240 105-115 14 24 0.30 105-115 12 12.0 105-115 12.5 192 50 105-115 22 360.35 105-115 20 20.0 105-115 20.5 352 40 105-115 25.8 36 0.40 105-115 2222.0 105-115 22.5 352 50 105-115 28 36 0.40 105-115 24 24.0 105-115 24.5352 50 105-115

TABLE VII Graft Graft Braid Bioabsorbable Bioabsorbable BioabsorbableBraid Strands in Graft Braid Mandrel Strands in Filament Dia., BraidAngle, Mandrel Graft Yam Angle, Dis., mm Braid mm Degrees Dia., mm BraidDenier Degrees 6 24 0.25 105-115 6.5 120 40 105-115 7 24 0.25 105-1157.5 120 50 105-115 8 24 0.25 105-115 8.5 120 50 105-115 9 24 0.25105-115 9.5 120 60 105-115 10 24 0.25 105-115 10.5 192 40 105-115 12 240.30 105-115 12.5 192 50 105-115 20 36 0.35 105-115 20.5 352 40 105-11522 36 0.40 105-115 22.5 352 50 105-115 24 36 0.40 105-115 24.5 352 50105-115

TABLE VIII Annealed Stent Braid Bioabsorbable Bioabsorbable Graft AnnealFilament Graft Mandrel Bioabsorbable Filament Braid Graft Braid MandrelAnnealed Crossing Braid Dia., Strands Dia., Angle, Yarn Angle, Dia.,Stent Angle, Angle, mm in Braid mm Deg. Denier Deg. mm I.D., mm Deg.Deg. 8 24 0.25 130-135 40 130-135 6 6.0 105-115 105-115 10 24 0.25130-135 50 130-135 7 7.0 105-115 105-115 10 24 0.25 130-135 50 130-135 88.0 105-115 105-115 12 24 0.25 130-135 60 130-135 9 9.0 105-115 105-11512.5 24 0.25 130-135 40 130-135 10 10.0 105-115 105-115 14 24 0.30130-135 50 130-135 12 12.0 105-115 105-115 22 36 0.35 130-135 40 130-13520 20.0 105-115 105-115 25.8 36 0.40 130-135 40 130-135 22 22.0 105-115105-115 28 36 0.40 130-135 50 130-135 24 24.0 105-115 105-115

Another embodiment of the stent-graft 100 includes at least onebioabsorbable-radiopaque marker strand disposed thereon to visualize theposition of the stent-graft 100 through fluoroscopy during implantation.

Bioabsorbable markers that may advantageously be used in conjunctionwith the present invention are disclosed in U.S. patent applicationsentitled “Radiopaque Markers And Methods Of Using Same”, Ser. No.08/905,821 (now U.S. Pat. No. 6,340,367) and “Bioabsorbable MarkerHaving Radiopaque Constituents And Method Of Using Same”, Ser. No.08/904,951 (now U.S. Pat. No. 6,174,330) both filed Aug. 1, 1997.

A delivery device is used for delivering the stent-graft 100 to atreatment site in a body vessel. Reference is made to FIG. 27 showing adelivery device 140 for delivering a stent-graft 100 to a treatment sitewithin a body lumen which is used to controllably release thestent-graft 100 within the lumen. The delivery device 140 generallyincludes an elongate and flexible outer catheter 20 constructed of abiocompatible polymer such as polyurethane. A central lumen 22 runs thelength of catheter 20. A distal end region 24 of the outer cathetersurrounds stent-graft 100. An inner catheter 26 is contained withinlumen 22 and runs along the entire length of the outer catheter. At thedistal end of inner catheter 26 is a tapered distal tip 28 which extendsbeyond the outer catheter. Stent-graft 100 surrounds inner catheter 26,confined between the inner and outer catheters. A lumen 30 in the innercatheter can accommodate a flexible guidewire (not shown) tracked bydelivery device 140 as it is advanced toward the treatment site.

Stent-graft 100 may be placed on the delivery device 140 in a radiallycompressed state. Preferred delivery devices are shown in U.S. Pat. Nos.4,954,126 and 5,026,377. Alternative delivery devices are shown in U.S.Pat. Nos. 5,201,757; 5,484,444; 5,591,172; 5,628,755; and 5,662,703.Suitable materials for use with such delivery devices are described inU.S. patent application Ser. No. 08/833,639, filed Apr. 8, 1997 (nowU.S. Pat. No. 6,042,578).

A pusher-type delivery system provides generally greater self-expansionof the stent-graft 100 than a coaxial inner-outer tube-type deliverysystem. Pushing the proximal end of the stent-graft 100 out the distalend of the delivery system results in more self expansion than when thestent is released by sliding back the outer tube of the catheterdelivery system. The preferred delivery system size for stent-graft 100is the external diameter in French size of about 7-20 French (Frenchsize is equivalent to about three times the diameter in mm).

An alternative delivery device is shown in FIG. 28 where a distal endregion of a catheter 122 is used to deploy the stent-graft 100.Stent-graft 100 is designed to remain in the axially elongated, radiallyreduced delivery state as shown, without additional constrainingfeatures. An auxiliary forcing feature is required to urge thestent-graft 100, once properly positioned at a treatment site, towardits normal state. For this purpose a dilatation balloon 126 is mountedto catheter 122 and surrounded by the stent-graft 100. The balloon 126,when inflated by the introduction of fluid under pressure through alumen in catheter 122, radially expands the stent-graft 100.

Although the present invention has been described with reference topreferred embodiments, those skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the invention.

It will be evident from considerations of the foregoing that thebioabsorbable self-expanding stent-graft 100 may be constructed using anumber of methods and materials, in a wide variety of sizes and stylesfor the greater efficiency and convenience of a user.

The above described embodiments of the invention are merely descriptiveof its principles and are not to be considered limiting. Furthermodifications of the invention herein disclosed will occur to thoseskilled in the respective arts and all such modifications are deemed tobe within the scope of the invention as defined by the following claims.

1. A method of using a stent-graft comprising: providing a stent-graftassembly, said stent-graft assembly formed by the method comprising thesteps of: disposing a tubular body comprising bioabsorbable material ona mandrel; disposing a compliant and substantially non-absorbable graftlayer on the mandrel such that one of the tubular body and the graftlayer surrounds the other over at least a coextensive portion; and withthe tubular body and the graft layer so disposed, adhering the graftlayer to the tubular body with a bioabsorbable adhesive to form astent-graft in which the tubular body is radially expandable andcontractible and the graft layer tends to conform to the tubular body asthe tubular body radially expands and contracts; deploying thestent-graft assembly into a body lumen at a treatment site; and allowingthe stent-graft assembly to self-expand or expanding the stent-graftassembly in the body lumen.
 2. The method of claim 1, wherein saidtubular body is formed by helically winding a plurality of bioabsorbablefilaments.
 3. The method of claim 2, wherein said tubular body isannealed at a temperature between a glass transition temperature of thebioabsorbable filaments and a melting point of the bioabsorbablefilaments.
 4. The method of claim 3, wherein said annealing of thetubular body is performed after said adhering the graft layer to thetubular body.
 5. The method of claim 2, wherein said forming thebioabsorbable tubular body includes interbraiding the filaments.
 6. Themethod of claim 1, wherein said disposing the graft layer on the mandrelincludes surrounding the tubular body with the graft layer.
 7. Themethod of claim 1, wherein said disposing the graft layer on the mandrelincludes surrounding the graft layer with the tubular body.
 8. Themethod of claim 1, wherein said adhering the graft layer to the tubularbody comprises applying an adhesive only to proximal and distal endportions of the coextensive portion.